Ethers.js: Default solidity JSON ABI type not supported by Contract or Interface

[andrevmatos]

I'm creating contract instances by importing the JSON ABI (out of solidity, or as copied from etherscan contract page e.g.) in typescript and passing it to the constructor, but TypeScript complains the JSON (fully-declared) type can't be assigned to contractInterface: Array<string | ParamType> | string | Interface.
Example

import TokenAbi from './contracts/Token.json';
const contract = new Contract(tokenAddress, TokenAbi, signer);

Funny enough, a workaround seems to be just casting it as one of the union types, as the Interface constructor can handle the provided fragment array, but it's wrong.

The problem I see is that ParamType[] (the part of the union I suppose was expected to relate to this kind of use) isn't a valid ABI, as it'd represent just the type of a input or output of either a function or event. Instead, I'd say the correct interface for the Contract constructor would be something like:

contractInterface: Array<string> | Array<FunctionFragment | EventFragment> | string | Interface

This change could be reflected in the Interface constructor type as well.

Additionally, I believe the FunctionFragment.gas member should be made optional (?), as it isn't present in the JSON abi fragments.

[ricmoo]

So, it is important to note that your import from a JSON filename is not importing the value as JSON. It performs a JSON.parse, so it is actually an object. JSON is the string representation. So, if you pass in the JSON.stringify(TokenAbi), it will work fine, since it is a string, which is an allowed type. :)

It’s hard to accept a generic object in a type-safe way. I’ll look into expanding the fragment types, as this was something I wrote quite a while ago when still learning TypeScript.

[andrevmatos]

Right, when I wrote _JSON (fully-declared) type_ I was not precise, as I was trying to refer to the object type. The good part about is that, when importing a JSON file directly (with resolveJsonModule: true in tsconfig), TypeScript actually does a pretty good job in infering the resulting object's schema/type. So it wouldn't be a generic object, but instead a complete schema which can be made compatible with your current fragments with the types I mentioned, which could help on this. Doing a stringify would actually be more or less the same as casting it to the one of the supported types, as Interface's constructor would immediatelly parse it back and proceed as with the casted object. Fortunately, the Fragments types are already close enough (minus only that gas member) to the parsed ABI type, so it should be feasible to have proper typing for this usecase.
Thank you very much for your awesome work on this. It's a true pleasure to work with this library on https://github.com/raiden-network/light-client =)

[ricmoo]

(oh, and yes, gas should certainly be an optional property; only Vyper and the Human-Readable ABI format have wide support for it)

[ricmoo]

In your above example, can you try using TokenAbi.abi (instead of just TokenAbi)?

Looking more into that, I think that may be the issue. I have confirmed in v4 that gas is not verified at the TypeScript compiler level...

[andrevmatos]

On the JSON I mentioned, there's no abi, it already contains the ABI (it's a list of the fragments, as I mentioned), but because of that simple type mismatch, it isn't accepted. I'll try to prepare a PR with tests to implement it.
About gas, I understand it isn't verified nor expect to, just the property being required makes it incompatible with the common definition I mentioned, therefore it should be made optional.

[ricmoo]

Re-reading your original comment with inspecting the source more, I think it is a bug.

Looking at the Contract and Interface objects, it looks like I'm expecting an Array<string | ParamType>, but I think that should be Array<string | FunctionFragment | EventFragment>, which is what you were saying in the first place. I'm trying to figure out why I did that. I think early on before I have a "Fragment" type I was using "Param", and there was an issue with the refactor (renaming Param to ParamType instead of Fragment...

I just need to make sure this won't break anyone if I make the change, but if anyone passes in a param type, it will get cast to a fragment and fall apart in other unfortunate ways, so I think the change is safe. Testing right now...

[ricmoo]

I've made the changes. Can you try out 4.0.43 and let me know if there are any other problems?

Thanks! :)

[ksvirsky]

4.0.41:
TS2345: Argument of type '({ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; })[]' is not assignable to parameter of type 'string | (string | ParamType)[] | Interface'.
Type '({ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; })[]' is not assignable to type '(string | ParamType)[]'.

4.0.43:
TS2345: Argument of type '({ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; })[]' is not assignable to parameter of type 'string | (string | FunctionFragment | EventFragment)[] | Interface'.
Type '({ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; })[]' is not assignable to type '(string | FunctionFragment | EventFragment)[]'.
and
TS2345: Argument of type '({ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; } | { ...; })[]' is not assignable to parameter of type 'string | (string | FunctionFragment | EventFragment)[] | Interface'.
Type '({ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; } | { ...; })[]' is not assignable to type '(string | FunctionFragment | EventFragment)[]'.
Type '{ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; } | { "anonymous": boolean; "inputs": { "indexed": boolean; "internalType": string; "name": string; "type": string; }[]; "name": string; "type": string; } | { ...; } | { ...; }' is not assignable to type 'string | FunctionFragment | EventFragment'.
Type '{ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; }' is not assignable to type 'string | FunctionFragment | EventFragment'.
Type '{ "inputs": { "internalType": string; "name": string; "type": string; }[]; "payable": boolean; "stateMutability": string; "type": string; }' is missing the following properties from type 'FunctionFragment': name, constant, outputs

[andrevmatos]

Yes, this is failing in our repo too:
https://github.com/raiden-network/light-client/pull/892#issuecomment-575140079
Seems like fallback method doesn't comply with FunctionFragment. It may be needed to either add a FallbackFrament to the array union, or make FunctionFragment itself a union between current schema and the fallback schema ({ payable: boolean; stateMutability: string; type: "fallback"; })

[ricmoo]

Oh, that is interesting...

The library drops unknown types, but TS is a bit pickier, so I’ll add something for this Type. It won’t have its own fragment type in v4, but I’ll get TS to behave itself. And I’ll make sure v5 understands too.

What compiler version is this? I know 0.6 has added some new types, and in need to check on what the ABI puts in place of those new pseudo-functions...

[snario]

I am using 0.5.13+commit.5b0b510c.Darwin.appleclang and see this.

[andrevmatos]

@ricmoo I believe we used solidity 0.5.4+commit.9549d8ff to get these fallback methods

[ricmoo]

by the way, the rollback to include ParamType can be tracked here:

https://github.com/ethers-io/ethers.js/issues/721

[ricmoo]

I think this ticket is resolved now, no? I'm going to close it, but if it is still an issue, please re-open.

I've also published the fix for #721, but will leave that open a bit longer to make sure that problem is addressed too.

Thanks! :)

[ricmoo]

(also thanks for the Solidity version, I'll check out the generated ABI for that too)

[andrevmatos]

Yes, indeed the current version works for our usecase: the fallback function, of type { payable: boolean; stateMutability: string; type: string } is assignable to union member ParamType, which is { name?: string; type: string; indexed?: boolean: components?: Array<any> }, so the inferred abi type is assignable to the constructor parameter without casting.
Thanks!

[ricmoo]

Awesome! Glad to hear it. Yes, basically the ParamType is very forgiving, only requiring a "type", which is why it worked before. When I removed it, I was thinking that no one would pass in a ParamType to that function, but now I realize that people were passing things in that shared its shape. :)

In v5, this is replaced by the JsonFragment interface, which matches the types of things that Solidity outputs in its ABI.